Conference technology currently allows for video communications among participants in addition to audio communications. Typically a presenter will have two video streams at his disposal. The first stream may be considered a main video stream, which would show the output of the presenter's camera, e.g., the presenter's head shot. A second stream would be used for a presentation. Examples of a presentation could include a view of the presenter's computer desktop or the output of particular application, such PowerPoint™ or a web browser, for example.
The main video stream may have to capture motion, such as the gestures and facial movements of the presenter; the presentation stream does not necessarily have to accommodate significant motion. The motion video content of a Power Point™ presentation is generally minimal, for example. As a result the presentation stream is typically encoded at a lower frame rate than the main video stream. In some conferencing systems, the presentation stream may be encoded at 5 or 10 frames per second (fps), while the main stream may be encoded at 30 or 60 fps.
There may be situations, however, where the presentation stream of the conference call needs to accommodate video. The presenter may wish to share a video clip for example. The presenter may have a multimedia file that he wishes to share, or he may want to share a video being streamed from the Internet. In such cases, the presentation stream's limited frame rate of 5 or 10 fps may result in an unacceptably low quality viewing experience for the other participants in the conference call.